Apparatus has been developed in the past for conveying webs. For the purposes of this application, the term "web" refers to any continuous elongate strip of flexible material, and specifically includes, but is not limited to, a web constructed of a polymeric film having at least one surface coated with a pressure sensitive adhesive (i.e. tape). Typically, a web is most conveniently provided in roll form, with the web wrapped about a rigid cylindrical core. The web may be wound in roll form in alternate configurations, including, but not limited to, planetary rolls, level wound rolls, and webs wound according to U.S. Pat. Nos. 4,477,035 entitled "Winding a Package of Tape" issued on Oct. 16, 1984; 4,568,033 entitled "Winding a Package of Tape" issued on Feb. 4, 1986; and 4,603,817 entitled "Package of Tape" issued on Aug. 5, 1986, the contents of which are incorporated herein.
Web conveying apparatus may be provided to unwind a web from a roll of the web during manufacturing processes, such as to coat or treat the web. The web conveying apparatus may be incorporated into a tape applicator for applying a length of pressure sensitive adhesive tape to an object. Tape applicators used to apply a length of tape to a regular slotted carton (RSC) are known as case sealers. Similarly, web conveying apparatus may be provided to wind a web unto a core, such when a relatively wide web is unwound, passed through slitting apparatus to longitudinally divide the web into a plurality of parallel narrow webs, each of which is then wound unto a new core of correspondingly reduced width.
Whenever a web is conveyed, it is desirable that the position and movement of the web be controlled as the web is conveyed along a desired path. Conventional web conveying apparatus have therefore included structure for guiding the web as the web is being conveyed. Guide structures for conventional web conveying apparatus have included guide blocks or "shoes" mounted in the path of the web. The guide blocks have a stationary surface over which the web passes and may include a pair of longitudinally extending laterally spaced walls for constricting side to side movement of the web as it passes through the guide block. Alternatively, rollers have also been used and likewise mounted in the path of the web. Laterally spaced walls may also be employed as with the guide blocks.
These conventional stationary guide structures have not proved completely effective in eliminating or reducing fluctuations in the movement of a web as it is conveyed. Particularly for relatively thin flexible webs, lateral movement of the web may result in "edge folding" in which a portion of the tape is partially or wholly longitudinally inverted or folded back upon itself. If the web takes the form of a pressure sensitive adhesive tape, the inverted adhesive surface of the tape may be self adhering, or may adhere to the web conveying apparatus. In the case of a tape applicator, the pressure sensitive adhesive tape becomes inoperative if edge folding occurs.